1. Field of the Invention
This invention relates generally to absorption heating and cooling systems and methods and, particularly, to a high efficiency absorption heating and cooling system and method utilizing a microwave energy heat source.
2. Description of the Prior Art
Closed loop absorption refrigeration systems are known in the prior art having at least a condenser, a metering device, an evaporator, an absorber, a pump and a generator or reaction chamber, typically fired by fossil fuels or electrical energy.
The principles of the prior art absorption refrigeration systems are similar in many respects to typical compression type refrigeration systems. In the classic compression type refrigeration system, a refrigerant is alternately compressed and expanded. In a simple closed loop compression type refrigeration system, there is at least a compressor, an evaporator, a throttling or metering device, and a condenser. During one stage of the compression type refrigeration cycle, a low pressure refrigerant vapor enters the compressor. At this point in the cycle, work is required of the compressor in order to raise the pressure and the boiling point of the refrigerant vapor. In the next phase of the compression type refrigeration cycle, the high pressure, high temperature refrigerant vapor leaving the compressor is transferred through a heat exchanger called a condenser. A second fluid passes through the condenser in order to remove heat from the refrigerant vapor, thereby transforming the refrigerant vapor to a refrigerant liquid. As the refrigerant liquid exits the condenser, it leaves at the same pressure but at a lower temperature than it had upon entering the condenser.
Next, the refrigerant passes through a throttling device that reduces the pressure, temperature and boiling point of the fluid. In the last step of the typical compression type refrigeration cycle, refrigerant travels through an evaporator to receive heat from some other fluid in communication with the evaporator to achieve the desired cooling effect of this other fluid. Such a closed loop compression refrigeration cycle is duplicated in order to repetitively remove heat from a body of fluid in communication with the evaporator.
Absorption type refrigeration systems accomplish cooling effects in a comparable manner to that described for the typical compression type refrigeration system. The evaporator, condenser and the throttling device are substantially similar in the two systems. However, a major distinction between the two systems is in the method used to increase refrigerant pressure between the condenser and the evaporator. In the compression type system, the increase in pressure is accomplished by a mechanical means, namely the compressor. In the absorption type system, the increase in pressure is brought about by means of heating an absorbent/refrigerant fluid, such as a water/ammonia mixture. The absorption refrigeration system is based upon the phenomenon of the absorption of ammonia vapor by water at lower temperatures and the expulsion of ammonia vapor when the water/ammonia mixture is heated.
The absorption refrigeration system has certain advantages over compression type refrigeration systems. For example, the typical compressor used in compression type systems has a number of moving mechanical parts and is somewhat noisy. The absorption refrigeration system, lacking the compressor, significantly reduces the noise level of the system. Maintenance requirements are also reduced, since there are no moving compressor parts to wear out or require regular maintenance.
In the past, the primary heat source for the generator used in the absorption type refrigeration system was usually provided by steam, gas burners, or electric resistance heaters. For example, U.S. Pat. No. 4,914,919 shows an absorption refrigeration system operated by a heating cartridge from at least one electric current source or by a gas burner. Similarly, U.S. Pat. No. 4,487,030 shows another absorption refrigeration system which is operated by electrical resistance heaters or by flammable gas burners.
The practical use of these prior art absorption refrigeration systems was significantly limited due to several disadvantages associated with the heat source used by the generator of these and other comparable systems. In particular, the overall system efficiency of most of these prior art systems which used relatively inefficient generator heat sources was appropriately low in comparison to the system efficiency of most non-absorption type refrigeration systems. In addition, most of the heating sources used by the generator in these prior art absorption systems required frequent and costly maintenance.
A need exists to provide an absorption refrigeration system having a high efficiency and a low maintenance heat source for use in the system generator or reaction chamber which increases the overall thermal efficiency of the system while decreasing the amount of routine maintenance which must be performed on this component of the absorption refrigeration system.
A need also exists for an absorption refrigeration system in which the refrigerant vapor is extracted from the absorbent/refrigerant mixture at the lowest possible temperature while achieving a high purity vapor.
A need also exists for an absorption refrigeration system which can be operated in a heating mode by changing the flow path of the absorbent/refrigerant fluid in the system.
A need also exists to provide an absorption refrigeration system which is more thermally efficient and yet which is cost effective and competitive with existing compression refrigeration systems in price.
The foregoing needs present in the prior art absorption refrigeration systems are met, in part, according to the teachings of the present invention by replacing the generator heat source of the prior art systems with a microwave energy source to heat the liquid absorbent/refrigerant mixture in the generator or reaction chamber. These needs are further met by electrolyzing the absorbent/refrigerant mixture in the generator chamber by subjecting the mixture to an ionizing current in addition to the microwave energy source. These needs are also met by passing the absorbent/refrigerant mixture from the generator chamber through an electromagnetic vapor scrubber to further ionize the fluid and extract the refrigerant vapor from the absorbent at the lowest possible temperature while achieving a high purity vapor. The absorption refrigeration system of the invention then becomes a more thermally efficient, cost effective and low maintenance system.